Intraocular lenses are widely known in opthalmology; for example, intraocular lenses are implanted in the event of opacification of the originally clear eye lens (cataract).
Age-related long-sightedness (presbyopia) is a particular problem in opthalmological, cf. for example the article “Intraokularlinsen”, in DER AUGENSPIEGEL, July-August 2002: 28-34. The age-related loss of elasticity of the natural eye lens prevents adaptation of its refractive power and therefore accommodation of the eye to objects lying at close range in front of the eye, and sharp imaging thereof or the retina. Although the loss of accommodation ability can be corrected by reading glasses, this however entails the known outlay and inconveniences.
The prior art reveals a variety of attempts to resolve the problem of presbyopia:
For instance, there has been an attempt to displace artificial intraocular lenses (IOLs) by the action of the ciliary muscle of the eye (cf. the article cited above in “Der Augenspiegel”). This has, however, achieved only insufficient displacement of the IOL in the axial direction (conventionally referred to as the z axis) and therefore only an insufficient focal point displacement.
There has also been an attempt to deform a fitted IOL mechanically by the ciliary muscle, although it has not yet been possible to demonstrate success convincingly.
Another approach attempts to restore the elasticity of the natural eye lens by radial incisions in the crystalline eye lens with a non-invasive FS laser, cf. O. Kermani in “Neues aus Wissenschaft und Forschung”, J. Refract Surgery: 2004; 20:651-658. The elasticity is scarcely changed thereby, however, and there is the risk of an induced cataract.
Multifocal IOLs have furthermore been implanted, albeit with the known difficulties, in particular perturbing double images and lack of sharpness since at least two focal lengths with different imaging properties produce simultaneous double images on the retina, cf. “Neue Multifokallinsen, individuelle Lösungen und postoperative Funktionalität”, in Der Augenspiegel, September 2004:42-47.
Another attempt to alleviate presbyopia is to produce monovision by refractive laser surgery of the cornea. One eye is in this case corrected to the near point and the other eye is left adjusted to the far point, or corrected so that the latter is then usually the so-called leading eye. Then, however, the two eyes deliver different information which must be processed by the brain and taken in by the patient.